5 Which one of the statements below best describes the mechanism of protontranslocation by the Electron Transport System using a redox loopmechanism exemplified by the Q cycle?Protons located in the cytosol are translocated across the mitochondrialmembrane into the matrix by altering pKą values of functional groupslocated on the inner and outer faces of the membrane within the proteinchannel.A redox reaction results in a H* and e- that are separated within theelectron transport system and deposited on opposite sides of the outermitochondrial membrane, with protons on the negative side.When the e-binds to cytochrome c, it results in dissociation ofcytochrome c from complex II, which stimulates release of H* fromcomplex IV, and thereby translocates protons and electrons separately.A redox reaction separating protons and electrons within complex III ofthe electron transport system, with the protons be translocated to theinter-membrane space and the electrons used to reduce Q.

The Q cycle (named after quinol) is a set of reactions. The Q cycle describes how the sequential…

Answered: Which one of the statements below best…

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter2: Cell Physiology

Section: Chapter Questions

Problem 10RE: Using the answer code on the right, indicate which form of energy production is being described: 1....

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The Relative Efficiency of ATP Synthesis in Noncyclic versus Cyclic Photophosphorylation If noncyclic photosynthetic electron transport leads to the translocation of 7 H+/2e- and cyclic photosynthetic electron transport leads to the translocation of 2 H+/e-, what is the relative photosynthetic efficiency of ATP synthesis (expressed as the number of photons absorbed per ATP synthesized) for noncyclic versus cyclic photophosphorylation? (Assume that the CF1CF0-ATP synthase yields 3 ATP/14 H+.)
Which of the following statements concerning the complete oxidation of FADH2 in the electron transport chain is NOT true? a. In the final step, electrons from cytochrome c to O2 reducing it to H2O in complex IV, and four protons are transported from the intermembrane space to the matrix. b. In the first step, electrons from FADH2 are transferred in complex II to ubiquinone, which does not transport any proton across the inner mitochondrion membrane. c. In the second step, complex III transfers the electrons from ubiquinone to cytochrome c, and four protons are transported from the matrix to the intermembrane space. d. The complete oxidation of FADH2 causes transfer of 6 protons and yields two ATP.
The maintenance of a proton motive force across the inner mitochondrial membrane is crucial for continued ATP production. Surprisingly, it has been discovered that the inner membranes of certain cells contain proteins, called uncoupling proteins, that are capable of transporting protons from the intermembrane space to the mitochondrial matrix. Why would mitochondria contain transporters that essentially waste energy potential in the proton gradient?
Which of the following statements is true? A. The NADH dehydrogenase complex can pump more protons than can the cytochrome b-c1 complex. B. The pH in the mitochondrial matrix is higher than the pH in the intermembrane space. C. The proton concentration gradient and the membrane potential across the inner mitochondrial membrane tend to work against each other in driving protons from the intermembrane space into the matrix. D. The difference in proton concentration across the inner mitochondrial membrane has a much larger effect than the membrane potential on the total proton-motive force.
Electron transfer translocates protons from the mitochondrial matrix to the external medium, establishing a pH gradient across the inner membrane (outside more acidic than inside). The tendency of protons to diffuse back into the matrix is the driving force for ATP synthesis by ATP synthase. During oxidative phosphorylation by a suspension of mitochondria in a medium of pH 7.4,pH 7.4, the measured pH of the matrix is 7.7. Calculate [H+] in the external medium and in the matrix under these conditions. a)[H+]in the matrix: b)What is the outside‑to‑inside ratio of [H+]? c)What is the free‑energy change inherent in this concentration difference across the membrane? (Assume a temperature of 25 °C.25 °C.)
Given that malonate inhibits succinate dehydrogenase which of the following statements is TRUE? a. FADH2 results in only 4 H+ being pumped out of the mitochondrial matrix. b. All electron transport is inhibited. c. Transfer of electrons from NADH to Coenzyme Q (ubiquinone) is inhibited. d. Transfer of electrons from FADH2 to Coenzyme Q (ubiquinone) is inhibited. e. NADH results in only 4 H+ being pumped out of the mitochondrial matrix. Clear my choice
Which of the following statements is NOT true about the electron transport chain (ETC) and oxidative phosphorylation? (Only one answer applies) A. Oxidative phosphorylation requires the enzyme complexes to be soluble in the mitochondrial matrix. B. If the proton gradient is too high, electrons will not move through the ETC. C. The movement of electrons down the ETC only happens if protons are pumped out of the mitochondrial matrix. D. Oxidative phosphorylation requires the mitochondrial intermembrane space to be more positively charged than the matrix. E. The free energy of the proton gradient can be used to create high energy bonds.
During the FADH2 electron transport chain, the protons are pumped from the mitochondrial matrix to the intermembrane space through complexes CoQ/III, and IV the protons are pumped from the mitochondrial matrix to the intermembrane space through complexes I, CoQ/III, and IV the protons are pumped from the mitochondrial matrix to the intermembrane space through complexes I, CoQ/II, and IV the protons are pumped from the mitochondrial matrix to the outer mitochondrial membrane through complexes I, III, and IV
How is the energy used to make ATP via the electron transport chain generated? a. The energy from electrons bound to reduced coenzymes is used to create a steep electrochemical gradient. b. Electrons bound to NADH are used to generate a H+ ion gradient across the inner mitochondrial membrane. c. Electrons bound to FADH2 are used to generate a proton gradient across the inner mitochondrial membrane. d. Electrons bound to NADH are used to generate a proton gradient across the inner mitochondrial membrane. e. All of these are correct.
Which of the following statements is NOT true about the electron transport chain (ETC) and oxidative phosphorylation? A. Oxidative phosphorylation requires the enzyme complexes to be soluble in the mitochondrial matrix. B. If the proton gradient is too high, electrons will not move through the ETC. C. The movement of electrons down the ETC only happens if protons are pumped out of the mitochondrial matrix. D. Oxidative phosphorylation requires the mitochondrial intermembrane space to be more positively charged than the matrix. E. The free energy of the proton gradient can be used to create high energy bonds.
Electron transfer translocates protons from the mitochondrial matrix to the external medium, establishing a pH gradient across the inner membrane (outside more acidic than inside). The tendency of protons to diffuse back into the matrix is the driving force for ATP synthesis by ATP synthase. During oxidative phosphorylation by a suspension of mitochondria in a medium of pH 7.3, the pH of the matrix has been measured as 7.6. (a) Calculate [H+] in the external medium and in the matrix under these conditions. (b) What is the outside-to-inside ratio of [H+]? Comment on the energy inherent in this concentration difference (just the energy from the concentration gradient, not the electrochemical potential). Assume this a mammalian system, so the temperature is constant at 37oC). (c) Calculate the number of free protons in a respiring liver mitochondrion, assuming its inner matrix compartment is a sphere of diameter 1.6 microns. (volume of a sphere is 4/3 pi r3 )
The chemical coupling hypothesis (substrate-level phosphorylation) failed to explain why mitochondrial membrane mustbe intact during ATP synthesis. How does the chemiosmotictheory account for this phenomenon?

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